Hexedit is a full screen hex editor using the curses, ncurses, or pdcurses library.
Some of it's features are:
-Familiar setup, similar to Nortan's Diskedit.
-File Selection widget for selecting a file to edit.
-Editing and Viewing disks in Linux and OpenBSD.
-Allows Inserting and Deleting bytes from the file.
-Highlights changes in the file in bold.
-Fast boyer-moore string and byte searches.
-Undo - keeps track of all changes, reverting back to original always possible.
-Start of a base conversion/calculator utility built in.
-Portable. This should run on any platform with a dialect of the curses library.

Hexedit author is Adam Rogoyski who licensed it under GPL. For more information, visit the dedicated webpage on his website: http://www.rogoyski.com/adam/programs/hexedit/